Compilare: user.cpp:18: warning: ISO C++ forbids declaration of 'main' with no type user.cpp: In function 'int main()': user.cpp:24: warning: conversion lacks type at end of format user.cpp:24: warning: too many arguments for format user.cpp:28: warning: conversion lacks type at end of format user.cpp:28: warning: too many arguments for format user.cpp:28: warning: 'v' is used uninitialized in this function